Beaglebone: Difference between revisions

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=== Configure Eclipse for cross compile ===
=== Configure Eclipse for cross compile ===
http://zombiebabylabs.com/2014/02/hello-beaglebone-world-a-c-primer/
http://zombiebabylabs.com/2014/02/hello-beaglebone-world-a-c-primer/
=== GUI not shown up ===
http://www.marshut.com/xkshy/beaglebone-black-qt-gui-application.html


== GPIO Projects ==
== GPIO Projects ==

Revision as of 06:54, 23 March 2014

Official website

Basic

BeagleboneCup.jpg

Wiki, Blog, Resource

The meaning of LEDs in BBB board

  1. USR0 is configured at boot to blink in a heartbeat pattern
  2. USR1 is configured at boot to light during microSD card accesses
  3. USR2 is configured at boot to light during CPU activity
  4. USR3 is configured at boot to light during eMMC accesses

BlackUSR.png

Debian

Download from http://beagleboard.org/latest-images. Username: debian. Password: temppwd. This distribution contains graphical desktop environment.

BbbDebian.png

The Debian version can be found by (version 7 has a codename wheezy) 

debian@beaglebone:~$ cat /etc/debian_version 
7.4

microSD version

sudo dd bs=1M if=bone-debian-7.4-2014-03-04-2gb.img of=/dev/sdc
sudo sync

Hold the button close to microSD card and apply power.

emmc version

sudo dd bs=1M if=BBB-eMMC-flasher-debian-7.4-2014-03-04-2gb.img of=/dev/sdc
sudo sync

Ubuntu/Debian

  • Hold the S2 button & power on BBB. 1st and 3rd LEDs blink.

eMMC version (info was outdated now)

  1. wget the image
  2. Use sudo su instead su to have full root permission. Use xz command to write the image to microSD
  3. Insert microSD to BBB and holding the button (closest to microSD) while applying power on BBB
  4. To copy the image to eMMC, use wget again to get the image file. Use sudo su instead su to have full root permission. Then use xz command again to write the image to eMMC.
  5. Remove microSD and reboot BBB. If we keep microSD in BBB, it will boot from microSD. MicroSD has the advantage that we can extend the space while eMMC cannot.
  • Kernel is 3.8.
  • The image contains a miniminal Ubuntu system. It only takes 276 MB when I use df -h command to check. So it does not come with a full desktop.
  • Defautl username=ubuntu, password=ubuntu
  • http://robotic-controls.com/learn/beaglebone/beaglebone-black-ubuntu
  • If I try to install xubuntu-desktop, it requires 421MB data to download and 1.2GB space to install. So it is not feasible since the /dev/mmcblk0p2 partition has only 1.8GB space. Fortunately, the solution in here works well.
  • Unfortunately, I got an error when I issue 'startx'.
Fatal server error:
AddScreen/ScreenInit failed for driver 0

Please check the log file at "/var/log/Xorg.0.log" for additional informaiton.

After I reboot, things looks better. I can get a login GUI. However, the system is very slow and I can not see mouse on the desktop.

microSD version (with LXDE desktop environment)

PS. Even the emmc version contains LXDE environment. Download from http://beagleboard.org/latest-images

At the beginning, the "/" partition still has 1.4GB space (see table below). If we boot into microSD (using ssh [email protected]) and follow the instruction or this to expand the microSD file system, we can make use whole space in uSD. It involves two commands: one is fdisk and the other is resize2fs. 

debian@beaglebone:~$ df -h
Filesystem      Size  Used Avail Use% Mounted on
rootfs           15G  1.3G   13G  10% /
udev             10M     0   10M   0% /dev
tmpfs           100M  616K   99M   1% /run
/dev/mmcblk0p2   15G  1.3G   13G  10% /
tmpfs           249M     0  249M   0% /dev/shm
tmpfs           249M     0  249M   0% /sys/fs/cgroup
tmpfs           100M     0  100M   0% /run/user
tmpfs           5.0M     0  5.0M   0% /run/lock
/dev/mmcblk0p1   96M   69M   27M  72% /boot/uboot
/dev/mmcblk1p2  1.7G  1.3G  345M  79% /media/rootfs
/dev/mmcblk1p1   96M   72M   25M  75% /media/boot

To find out the Debian version, use 

cat /etc/debian_version

Console version

Following the instruction on robotic-controls.com, we can install the console version of Ubuntu on BBB. The image I download is Ubuntu 13.10 https://rcn-ee.net/deb/rootfs/saucy/ubuntu-13.10-console-armhf-2013-11-15.tar.xz.

This image has some features like 192.168.7.2 access automatically just like Angstrom distribution (I don't know how to get this to work on eMMC version of Ubuntu image). That means I can just connect to BBB without using ethernet under Ubuntu OS.

Installation script (uSD is mounted on /dev/sdc in my case) 

wget https://rcn-ee.net/deb/rootfs/saucy/ubuntu-13.10-console-armhf-2013-11-15.tar.xz
tar xJf ubuntu-13.10-console-armhf-2013-11-15.tar.xz
cd ubuntu-13.10-console-armhf-2013-11-15
sudo ./setup_sdcard.sh --mmc /dev/sdc --uboot bone

The username/password is ubuntu/temppwd.

Below is what I get in HOST os 

brb@brb-P45T-A:~/ubuntu-13.10-console-armhf-2013-11-15$ ifconfig
...
eth2      Link encap:Ethernet  HWaddr 90:59:af:63:df:45  
          inet addr:192.168.7.1  Bcast:192.168.7.3  Mask:255.255.255.252
          inet6 addr: fe80::9259:afff:fe63:df45/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:9 errors:0 dropped:0 overruns:0 frame:0
          TX packets:47 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:1010 (1.0 KB)  TX bytes:11690 (11.6 KB)
...

and what I get inside BBB 

ubuntu@arm:~$ ifconfig
eth0      Link encap:Ethernet  HWaddr 90:59:af:63:df:43  
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
          Interrupt:56 
...
usb0      Link encap:Ethernet  HWaddr c6:18:a5:e4:60:71  
          inet addr:192.168.7.2  Bcast:192.168.7.3  Mask:255.255.255.252
          inet6 addr: fe80::c418:a5ff:fee4:6071/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:178 errors:0 dropped:0 overruns:0 frame:0
          TX packets:100 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:22583 (22.5 KB)  TX bytes:20013 (20.0 KB)
ubuntu@arm:~$ df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/mmcblk0p2   15G  493M   14G   4% /
none            4.0K     0  4.0K   0% /sys/fs/cgroup
udev            247M  4.0K  247M   1% /dev
tmpfs            50M  236K   50M   1% /run
none            5.0M     0  5.0M   0% /run/lock
none            248M     0  248M   0% /run/shm
none            100M     0  100M   0% /run/user
/dev/mmcblk0p1   64M   17M   47M  27% /boot/uboot

We can make the Ubuntu talk to internet by using the instruction given in Angstrom section (run sudo su first).

TTL/Serial cable connection

The screenshot below shows we can use a ttl serial cable to log into beaglebone in command line mode. The beaglebone is powered by a 5v usb. The tricky part is the J4 pin （RXD） in BBB should be connected to the TXD pin in ttl cable. Similarly, the J5 （TDX） pin in BBB should be connected to the RXD pin 8n ttl cable. The 3.3v p8n in ttl cable is not used at all.

This post asks NOT to connect the 5V pin from TTL to BBB. The Serial port pin settings is given on elinux.org as linked from codechiefl.wordpress.com.

Check out the beaglebone black system manual (Section 7.5 Serial Header) about the serial debug ports from https://github.com/CircuitCo/BeagleBone-Black/blob/master/BBB_SRM.pdf. 

   BBB        TTL
  ==========
   J1 GND    GND
   J4 (RXD)  TX
   J5 (TXD)   RX

Ftdi2ttlserialcable.jpg

Find out the IP address if we use internet sharing

If we are using ethernet on BBB, we can find out the IP adress by using the following way.

Download fing deb package from overlooksoft website. Install it by double clicking the file in file manager. Issue the following command to find out the IP of beaglebone black (shared computer). The IP of my 2nd ethernet adapter (eth1) is 10.42.0.1. 

sudo fing -n 10.42.0.1/24

Wifi setup command line

dmesg | grep rtl8192
ifconfig wlan0
sudo apt-get install wireless-tools
iwconfig
sudo nano /etc/network/interface
# Made appropriate change on /etc/network/interface
sudo ifup wlan0 // not needed if we have enable wlan0 at boot. 
                // sudo ifconfig wlan0 up
sudo iwlist wlan0 scanning
ping www.google.com

where the file /etc/network/interface should be like 

auto wlan0
iface wlan0 inet dhcp
    wpa-ssid mynetworkname
    wpa-psk mysecretpassphrase

Angstrom

# Umount the uSD card 
mount # find /dev/sdc1
sudo diskfutil unmount /dev/sdc1
ls *.xz

# Copy img file to microSD card. Took about 15-30 minutes.
# Method 1.
tar -xJf BBB-eMMC-flasher-2013.06.20.img.xz
sudo dd bs=1m if=~/Downloads/BBB-eMMC-flasher-2013.06.20.img of=/dev/sdc
sudo sync
# Method 2.
xz -cd BBB-eMMC-flasher-2013.06.20.img.xz > /dev/sdc

Remove the microSD card and insert it fully into BBB uSD card slot.

To flash the BBB: Hold down the 'user boot' button (closes to uSD card slot) and power on BBB until the 4 LED's light up for a few seconds. It will take 30-45 minutes to flash the image onto the eMMC. Once it's done, the 4 LED's will all stay lit up at the same time. You can then power down your BBB, remove uSD and power up BBB.

The username is root. There is not password. We can access it by ssh [email protected].

If we type ifconfig in Angstrom, we find the connection is through usb0 adapter. 

root@beaglebone:~# ifconfig
eth0      Link encap:Ethernet  HWaddr 90:59:AF:63:DF:43  
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
          Interrupt:56 

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:12 errors:0 dropped:0 overruns:0 frame:0
          TX packets:12 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:760 (760.0 B)  TX bytes:760 (760.0 B)

usb0      Link encap:Ethernet  HWaddr 86:27:86:2D:45:5C  
          inet addr:192.168.7.2  Bcast:192.168.7.3  Mask:255.255.255.252
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:2765 errors:0 dropped:0 overruns:0 frame:0
          TX packets:5003 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:179578 (175.3 KiB)  TX bytes:7067277 (6.7 MiB)

Web server

http://stackoverflow.com/questions/10818459/where-is-the-web-server-root-directory-on-angstrom-linux-beagleboard-beaglebo

Google coder

http://www.adafruit.com/blog/2013/09/17/run-google-coder-on-your-beaglebone-black/

VNC

opkg update
opkg install x11vnc

x11vnc -bg -o %HOME/.x11vnc.log.%VNCDISPLAY -auth /var/run/gdm/auth-for-gdm*/database -display :0  -forever

To start VNC server at bootup and shutdown, check out

Package download

http://www.gigamegablog.com/2012/01/29/beaglebone-linux-101-configuring-angstrom-linux/ 

opkg update
opkg install XXXX
opkg list | grep "gfortran"

However, at least for BBB case, I cannot find gfortran package so I cannot install R. See discussions below

The angstrom linux package browser is the place we can see if packages for BBB Cortex-A8. According to Wikipedia the Cortex-A8 has armv7a architecture.

On ubuntu, we can use ldconfig -v command to show the installed libraries and their versions. See here. If we like to manually add libraries to ubuntu/debian, we can check the tip here.

beaglebone.local and Avahi/Bonjour/Zeroconf

Instead of typing an IP address, we can use [email protected] to access BBB running on Angstrom OS. The implementation is done by Avahi Daemon/Bonjour/ZeroConf/Multicast.

We can manually install avahi-daemon in ubuntu-armhf by 

sudo apt-get update
sudo apt-get install avahi-daemon

After that, we should be able to ssh [email protected] instead of using IP. PS: not stable. 

brb@brb-P45T-A:~$ ssh [email protected]
ssh: connect to host ubuntu-armhf.local port 22: Connection refused

The real IP address can be found by ping HOSTNAME.local (Updated: use ps -ef | grep avahi to find out the exact hostname used in .local domain because at least one of my Ubuntu machines does not use its hostname exactly)

For the Angstrom OS with beaglebone, I found the IP number is in 192.168.7.2 (same as in the Getting Start page) by using ping command. 

brb@brb-P45T-A:/etc/init$ ping beaglebone.local
PING beaglebone.local (192.168.7.2) 56(84) bytes of data.
brb@brb-P45T-A:/etc/init$ ifconfig
(skip)
eth2      Link encap:Ethernet  HWaddr 90:59:af:63:df:45  
          inet addr:192.168.7.1  Bcast:192.168.7.3  Mask:255.255.255.252

The same method can be applied to Raspberry Pi or Ubuntu. In fact, avahi-daemon is installed by default. We can use ps -ef | grep avahi to check it.

Internet over Ethernet

The host has IP 10.42.0.1 and it is configured as shared instead of DHCP.

The BBB will have eth0: 10.42.0.50 and usb0: 192.168.7.2.

We can use ssh [email protected] to access it. The BBB will have internet access. 

echo "nameserver 8.8.8.8" > /etc/resolv.conf

Internet over USB

On BBB, run 

/sbin/route add default gw 192.168.7.1
echo "nameserver 8.8.8.8" >> /etc/resolv.conf

(IP Masquerade/Share the internet connection + IP forward) On host, run 

sudo iptables -A POSTROUTING -t nat -j MASQUERADE
echo 1 | sudo tee /proc/sys/net/ipv4/ip_forward > /dev/null

Done. Tested on my home ubuntu host machine running 12.04.

Recall that we can use the following command to show nat table on host machine. 

iptables -t nat -L

Angstrom

http://beaglebone.cameon.net/home/internet-over-usb

ArchLinux

This post on Archlinux discusses how to get the usb network adapter that is built into the mini-usb power connector working under Arch.

Ubuntu

How to share internet over USB on BBB? http://askubuntu.com/questions/380810/internet-over-usb-on-beaglebone-black

microHDMI to VGA cable

http://circuitco.com/support/index.php?title=BeagleBone_Black_Accessories

Question: How to create EDIT? My NEC monitor supports only 1024 x 768.

Beagleboneblack HDMI page from circuitco.com.

Remote desktop connection

See Raspberry#Connection_to_Raspberry_Pi_with_tightvnc 

# Server side
sudo apt-get install tightvncserver
tightvncserver     # set up the password
vncserver          # this step may not be necessary
vncserver –kill :1

# Client side
xtightvncviewer 10.42.0.50:1 # or xtightvncviewer 192.168.7.2:1 if we use usb0

To start tightvncserver automatically at start, follow the instruction at here to create a new script file under /etc/init.d/ directory and run update-rc.d on the new script. 

debian@beaglebone:~$ sudo nano /etc/init.d/vncserver
[sudo] password for debian: 
debian@beaglebone:~$ sudo chmod +x /etc/init.d/vncserver 
debian@beaglebone:~$ sudo update-rc.d vncserver defaults
update-rc.d: using dependency based boot sequencing
update-rc.d: warning: default start runlevel arguments (2 3 4 5) do not match vncserver Default-Start values (S)
update-rc.d: warning: default stop runlevel arguments (0 1 6) do not match vncserver Default-Stop values (0 6)
insserv: Script vncserver is broken: incomplete LSB comment.
insserv: missing `Required-Stop:'  entry: please add even if empty.
debian@beaglebone:~$ sudo reboot

Despite the warning, it still works. It make a copy of this vncserver file below. Something we may want to change for different scenario is the USER and GEOMETRY parameters. 

#!/bin/sh -e
### BEGIN INIT INFO
# Provides:          vncserver
# Required-Start:    networking
# Default-Start:     S
# Default-Stop:      0 6
### END INIT INFO

# PATH="$PATH:/usr/X11R6/bin/"

# The Username:Group that will run VNC
export USER="debian"
#${RUNAS}

# The display that VNC will use
DISPLAY="1"

# Color depth (between 8 and 32)
DEPTH="16"

# The Desktop geometry to use.
#GEOMETRY="<WIDTH>x<HEIGHT>"
#GEOMETRY="800x600"
GEOMETRY="1024x768"
#GEOMETRY="1280x1024"

# The name that the VNC Desktop will have.
NAME="my-vnc-server"

OPTIONS="-name ${NAME} -depth ${DEPTH} -geometry ${GEOMETRY} :${DISPLAY}"

. /lib/lsb/init-functions

case "$1" in
start)
log_action_begin_msg "Starting vncserver for user '${USER}' on localhost:${DISPLAY}"
su ${USER} -c "/usr/bin/vncserver ${OPTIONS}"
;;

stop)
log_action_begin_msg "Stoping vncserver for user '${USER}' on localhost:${DISPLAY}"
su ${USER} -c "/usr/bin/vncserver -kill :${DISPLAY}"
;;

restart)
$0 stop
$0 start
;;
esac

exit 0

My Observation about angstrom distribution

When I use the image BBB-eMMC-flasher-2013.06.20.img to put it on the microSD card with win32DiskImager, I see (from plugging SD in Ubuntu) the microSD card has 2 partitions 

eMMC-Flasher  -ext4
BEAGLE_BONE - vfat

where eMMC-Flasher contains an ubuntu data and BEAGLE_BONE contains only 4 files. 

ID.txt - just one line
MLO - 98K binary
u-boot.img - 371K binary
uEnv.txt - just one line

Flashing is done by pressing the 'Boot' button while connecting the power. It took 1 hour in my case when I flashed BBB-eMMC-flasher-2013.06.20.img.

However, once the microSD is flashed to eMMC, the 'eMMC-Flasher' partition will be gone and 'BEAGLE_BONE' partition is changed to include 3 new folders- App, Docs and Drivers AND some new files - START.htm, autorun.inf, README.md.

Android OS

Books

BBB vs Raspberry Pi

Beaglebone 101

Angstrom includes a web server running on BBB. The web address is http://192.168.7.2

I have created screenshots in Google drive http://goo.gl/o03iex

Fix date/time

See here. Run the following to change the country and time zone. 

sudo dpkg-reconfigure tzdata

Use microSD as ext storage

It is possible. See the idea in here.

Build R on BBB

I am using Ubuntu 13.04 image since angstrom linux missing many required packages.

Since the space is limited, instead of using 'sudo apt-get build-dep r-base', I manually install the essential packages: build-essential, gfortran, libreadline6-dev, libx11-dev, libxt-dev and openjdk-7-jre.

I am using R 3.0.1. 

ubuntu@ubuntu-armhf:~$ df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/mmcblk0p2  1.8G  276M  1.4G  17% /
none            4.0K     0  4.0K   0% /sys/fs/cgroup
devtmpfs        248M  4.0K  248M   1% /dev
none             50M  220K   50M   1% /run
none            5.0M     0  5.0M   0% /run/lock
none            248M     0  248M   0% /run/shm
none            100M     0  100M   0% /run/user
/dev/mmcblk0p1 1004K  472K  532K  48% /boot/uboot

sudo apt-get update
sudo apt-get install build-essential
sudo apt-get install gfortran
sudo apt-get install libreadline6-dev
sudo apt-get install libx11-dev
sudo apt-get install libxt-dev
sudo apt-get install openjdk-7-jre    
// (optional) need it if we don't want to get an error message at the end of running 'make'
// This require 143MB space.

// The whole process (configure + make) takes at least 2 hours on BBB
./configure --enable-R-shlib
make
// make > ~/Rmake.txt 2>&1

There is still warnings with library/datasets
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=695411
It seems this is false alarm.

ubuntu@ubuntu-armhf:~/R-3.0.1$ df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/mmcblk0p2  1.8G  1.1G  615M  64% /
none            4.0K     0  4.0K   0% /sys/fs/cgroup
devtmpfs        248M  4.0K  248M   1% /dev
none             50M  224K   50M   1% /run
none            5.0M     0  5.0M   0% /run/lock
none            248M     0  248M   0% /run/shm
none            100M     0  100M   0% /run/user
/dev/mmcblk0p1 1004K  472K  532K  48% /boot/uboot

The complete process of running ./configure and make are recorded in

Other configure options

http://cran.r-project.org/doc/manuals/R-admin.html#Configuration-on-a-Unix_002dalike 

./configure --disable-byte-compiled-packages --enable-R-shlib

Performance test

Qt cross compile

sudo apt-get install gcc-arm-linux-gnueabi

What's wrong when running a binary created on x86_64 OS

For the hello world example, I will get an error in BBB if I just scp the binary file from x86_64 OS to BBB. 

debian@beaglebone:~$ ./a.out
-bash: ./a.out: cannot execute binary file

What we should do to compile hello.c

arm-linux-gnueabi-gcc -march=armv7-a -mtune=cortex-a8 -mfpu=neon -o hello hello.c
scp hello [email protected]:

Then we run hello program in BBB. It should run successfully.

http://www.valvers.com/embedded-linux/beaglebone/step06-cross-compiling

What we should do to compile hello.cpp

Note: do not install g++-arm-linux-gnueabihf package. It will give me the following error when I try to compile a simple cpp program. 

warning: ld-linux.so.3, needed by /usr/lib/gcc/arm-linux-gnueabihf/4.6/libstdc++.so, not found (try using -rpath or -rpath-link)

According to the above website or michaelhleonard.com we shall install the toolchain 

sudo apt-get install gcc-arm-linux-gnueabi
sudo apt-get install g++-arm-linux-gnueabi

I can build hello.cpp on my x86_64 host. 

arm-linux-gnueabi-g++ -march=armv7-a -mtune=cortex-a8 -mfpu=neon -o hellocpp hello.cpp

But when I run the hellocpp program, I get the following error 

debian@beaglebone:~$ ./hellocpp
./hellocpp: error while loading shared libraries: libstdc++.so.6: cannot open shared object file: No such file or directory

I also try the following. It is a big download but still does not help. 

sudo apt-get install ia32-libs

Some people suggested to add the following when compiling your program 

-static -static-libstdc++

It works!!! The complete compile command is (-static-libstdc++ is not necessary) 

arm-linux-gnueabi-g++ -march=armv7-a -mtune=cortex-a8 -mfpu=neon -static -o hellocpp hello.cpp

Configure Eclipse for cross compile

http://zombiebabylabs.com/2014/02/hello-beaglebone-world-a-c-primer/

GUI not shown up

http://www.marshut.com/xkshy/beaglebone-black-qt-gui-application.html

GPIO Projects

Setting up an IO python library (GPIO, PWM, ADC, I2C, SPI, UART)

http://learn.adafruit.com/setting-up-io-python-library-on-beaglebone-black

  • PWM: P8_13, P8_34, P8_36, P8_45, P8_46, P9_14, P9_21, P9_22, P9_29, P9_42. Eg. blink LED, fading LED, servo.
  • ADC: P9_33, P9_35, P9_36, P9_37, P9_38, P9_39, P9_40. Eg. measure light, ultrasonic sensor, accelerometer, joystick, Potentiometer.
  • I2C: P9_19, PI_20. Eg. temperature/pressure sensors.
  • SPI: P9_17, P9_18, P9_21, P9_22, P9_28, P9_29, P9_30, P9_31.
  • UART: 17 pins.

Adding a push button

http://learn.adafruit.com/connecting-a-push-button-to-beaglebone-black

Measure light

http://learn.adafruit.com/measuring-light-with-a-beaglebone-black My example: 

import Adafruit_BBIO.ADC as ADC
import time
from time import localtime, strftime

sensor_pin = 'P9_40'

ADC.setup()

#print('Reading\t\tVolts')
print time.asctime(time.localtime(time.time())), '\tReading\t\tVolts'

while True:
    reading = ADC.read(sensor_pin)
    volts = reading * 1.800
    #print('%f\t%f' % (reading, volts))
    #print(strftime("%Y-%m-%d %H:%M:%S", localtime()))
    print time.asctime(time.localtime(time.time())), '\t%f\t%f' % (reading, volts)
    time.sleep(60)

which can be run (and the output was written to a file for logging) 

sudo python light.py > tmp.txt

If we want, we can follow the tutorial in here to have the light reading logged on the COMS or send to google docs like [1]. Alternatively, we can let BBB to send an email to you like here.

Fading RGB using PWM

http://learn.adafruit.com/fading-a-rgb-led-on-beaglebone-black/overview

Blinking an LED

http://learn.adafruit.com/blinking-an-led-with-beaglebone-black

Controlling a servo

We can actually try the following simpler approach using bonescript without bothering a command line. Just open a browser tab and type the address http://beagleboard.org/Support/BoneScript/ServoMotor/. It just works! The SG90 micro motor operators at 4.0 to 7.2 volts according to here.

BBBservo.jpg

Measuring temperature

http://learn.adafruit.com/measuring-temperature-with-a-beaglebone-black

HC-SR04 (5v) sonar sensor

http://www.youtube.com/watch?v=bssyOCcU_Q4

Connect to 5v device

See 3.2.4 of the book "Bad to the Bone".

Input voltage & voltage divider

http://beagleboard.org/Support/BoneScript/accelerometer/

PIR motion sensor (ADC)

http://beagleboard.org/Support/BoneScript/PIRMotionSensor

Pull-up Resistor

A very simple robot

http://beaglebone.cameon.net/beaglebone-robotics/1-robot-platform

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